Fluid ejection structures dispense drops based on input digital data. Typical fluid ejection structures include nozzle arrays in a nozzle plate to dispense fluid. The nozzle arrays may be arranged at a relatively high resolution to be able to dispense at high precision. Some fluid ejection structures are provided with thermal resistors near the nozzles to eject fluids out of the nozzles. To create a firing event with thermal resistors, a current is passed through the resistor, which rapidly heats up and vaporizes a thin layer of fluid near the resistor. The liquid-to-vapor transition creates an expanding bubble near the body of fluid in the firing chamber and ejects a droplet out through the nozzle. Insulating oxide layers are commonly present beneath the resistor in order to direct heat towards the fluid in the firing chamber.